Hydraulically compensating mechanism for valve lifters



A. CELL! Feb. 25, 195s HYDRAULICALLY COMPENSATING MECHANISM FOR VALVE LIFTERS Filed Nov. 17, 1954 IN V EN TOR.

ALDO CELL! BY Attorney United States Patent HYDRAULICALLY COMPENSATING MECHANISM FOR VALVE LIFTERS Aldo Celli, Oshkosh, Wis.

Application November 17, 1954, Serial No. 469,336

1 Claim. (Cl. 12390) This invention relates generally to hydraulic valve lifters and more specifically to a hydraulic compensating mechanism adapted to maintain substantially zero clearance in the valve drive train of an internal combustion engine.

Valve litters of the mechanical type presently used commercially do not provide for automatic adjustment of the valve drive train, nor for automatic elimination of backlash in the valve operating mechanism of an internal combustion engine. In mechanical drive trains, lost motion or clearance is provided between the rocker arms of the drive train and the stems of the valves. As the engine is operated, the lost motion is increased due to the impact and wear to which the train is subjected. Increased lost motion between the rocker arms and valve stems results in inefiicient and noisy operation of the engine and requires a partial disassembly of the engine to adjust the tappets; that is, to temporarily correct the lost motion between the rocker arms and valve stems by efiecting a manual adjustment in the drive train.

To avoid the necessity of frequent tappet adjustments and to eliminate noisy and inefficient operation of the engine, some commercial engines are equipped with bydraulic valve lifters which attempt to effect automatic adjustment of the valve' drive train to maintain zero lost motion in the train, so that in effect, the train functions as a solid body in opening the valves in the engine.

It is therefore an object of the present invention to provide an improved hydraulic compensating mechanism for a drive train capable of constantly and consistently maintaining zero lost motion and effectively eliminating backlash in the valve drive train of an internal combustion engine.

Another object of the invention is to provide an improved hydraulic compensating mechanism for a drive train of simpler design and containing a smaller number of moving parts than presently used commercial hydraulic valve lifters.

Another object of the invention is to provide an improved hydraulic valve lifter mechanism that is more compact, easier to assemble and disassemble and is more economical than prior known hydraulic valve lifter mechanisms.

Another object of the invention is to provide a hydraulic compensating mechanism for a drive train that is not subjected to constant reciprocal motion and therefore is more reliable than prior known valve lifter mechanisms.

Another object of the invention is to provide a hydraulic valve lifter mechanism that may readily be substituted for any and all valve lifter mechanisms presently used commercially, whether mechanical or hydraulic.

Objects and advantages other than those set forth above will be apparent from the following description when read in connection with the accompanying drawing, in which:

Fig. 1 is a fragmentary elevation view partially in section of an internal combustion engine embodying the invention;

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Fig. 2 is a fragmentary elevation view in section taken along line 22 of Fig. 1;

Fig. 3 is a plan view of Figure 2; and

Fig. 4 is a section view taken along line 4-4 of Figure 2.

As shown in the drawings, a preferred embodiment of this invention is illustrated as applied to the cylinder head 1 of a conventional internal combustion engine having a plurality of valves 2, only one of which is shown. A valve drive train indicated generally as 3 is provided, as is well understood, for each valve 2 of the engine, and the valve drive train 3 is conventional in all respects except for the hydraulic compensating mechanism 4 of the present invention, which is embodied therein. The valve drive train 3, as shown, extends between a cam shaft 5 of the engine and the valve 2. The cam shaft 5 is journaled in suitable bearings (not shown) carried by the crankcase 6, and the crankcase 6 is provided with cylindrical openings 7 adjacent a cam 8 of the cam shaft 5. A generally upwardly dished cylindrical cam follower 9 is loosely disposed in the cylindrical opening 7 and has a flat end portion 11 adapted to ride on the cam 8. As the cam 8 is rotated, the follower 9 reciprocally moves within the cylindrical opening 7. The inner portion of the follower 9 has a semi-spherical recess 12 forming a seat for one end of a hollow push rod 13. The other end of the push rod 13 which is rounded mates with a semi-spherically shaped shoulder portion 14 forming one of the ends of a rocker arm 15. A guide member 16 of generally U-shaped cross section having a flange 17 at one end is mounted on the cylinder head 1 by means of studs 18 and partially encircles the push rod 13 andshoulder portion 14 of the rocker arm 15 to'confine the movement of the drive train 3 in a fixed vertical plane. The rocker arm 15 is pivotably mounted intermediate its ends on a generally semi-spherical pivot member 19 whichforms a part of the hydraulic compensating mechanism of the invention and will be referred to in-greater detail hereinafter. The outer end of the rocker'arm 15 is adapted to bear against the free end of a stem 21 of the valve 2 to open'the valve. The valve 2 maybe of any known construction and the valve selected for illustration includes the aformentioned stem 21 guided in a collar part 22, and having spring means 23 associated therewith for normally tending to close the valve 2.

The hydraulic drive train compensating mechanism 4 of the present invention comprises a rod 24 having a threaded portion 25 at one end over which the pivot member 19 having an opening 26 therein is placed and secured thereto by means of a nut 27. The pivot member 19 mates with a corresponding semispherical seat 28 of the intermediate portion of the rocker arm 15 to form a pivot for the rocker arm. The rod 24 further is reciprocally movable in an elongated opening 29 formed by a cylindrical metal insert 31 mounted in the cylinder head 1. A piston 32 is mounted on the other end of the rod 24 for reciprocal movement in a cylinder 33 formed by the lower end of the cylindrical metal insert 31. The insert 31 is provided with an annular groove 34 near the top thereof into which an O-ring 35 or some other suitable member is placed to prevent oil leakage along the rod 24. An oil drain 36 shown as a hole connects the cylinder 33 to a suitable drain for conveying oil out of the cylinder that leaks past the piston 32. The cylinder head 1 further has a bore 37 to conduct oil under pressure from the pressure lubricating system of the engine through a channel 38 to a chamber 39 formed by an upwardly dished cylindrical member 41 mounted in the cylinder head 1. The chamber 39 has a ball check valve 42 positioned therein that mates with a beveled seat portion of the channel 38. The ball is urged into the seat portion by the action of a spring 44 disposed within the chamber 39 and held in place by means of a set screw 45 as is well known in the art. The cylinder head 1 also provides a passageway 43 connecting the chamber 39 to the cylinder 33 for conducting oil under pressure from the chamber 39 to the upper portion of the cylinder 33.

When the engine is started, oil from the pressure lubrication system under pressure in the range of forty to sixty pounds per square inch is conveyed through the bore 37 and thence through the channel 38 into the chamber 39 past the ball valve 42 and thence through the passageway 43 intothe cylinder 33 to force the piston 32, rod 24 and pivot member 19 downward to maintain the end of the rocker arm 15 in contact with the valve stem 21.

With the engine valve 2 in the open position, the various elements of the mechanism will assume the relative positions shown in Fig. 1, in which the follower 9 is engaged by the cam 8 and moved to its upward most position. In assuming this position, the upward movement of the follower 9 causes the push rod 13 to press upward against the shoulder portion 14 of the rocker arm 15 which causes the rocker arm to pivot about the pivot member 19. The other end of the rocker arm 15 is moved downwardly forcing the stem 21 of the valve 2 downwardly against the pressure exerted'by the spring 23, which is approximately two hundred to three hundred pounds per square inch. This action tends to force the piston 32, rod 24 and pivot member 19 upwardly, which movement is prevented by the closing of the ball valve 42 cutting off any escape of the oil above the piston 32. Since oil is substantially incompressible, the rod 24 will remain relatively immovable. There will be a slight leakage of oil past the piston 32 into the cavity below the piston, but the period of a cycle during which the valve 2 is open is so short that the oil leakage past the piston 32 is negligible.

As the cam 8 is rotated clockwise, the pressure of the valve spring 23 is transmitted through the rocker arm 15 and push rod 13 to the follower 9 moving it downwardly. With the follower 9 at its lowest position, if lost motion or backlash should exist within the drive train 3, oil pressure acting upon the piston 32 will cause the rod 13 to move downwardly maintaining contact between all the parts of the drive train 3 and eliminating any lost motion or clearance therein. If in the same situation not enough 4 lost motion is available, that is if the pivot member 19 is too low so that the valve 2 is open when the follower 9 is at its lowest position, the valve spring 23 exerts sufficient pressure to force the pivot member 19, rod 24 and piston 32 upwardly with the piston allowing the required amount of oil leakage into the cavity below the piston 32 to permit the valve 2 to close.

Although only one embodiment of the invention has been illustrated and described, it will be apparent to those skilled in the art that various changes and modifications of the invention may be made without departing from the spirit of the invention or from the appended claim.

Having thus disclosed my invention, I claim:

In a valve drive train comprising a cam follower, a push rod and a rocker arm for opening and closing a valve in an engine comprising a cylinder and a cylinder block, a hydraulic mechanism for supporting and maintaining zero clearance in said drive train comprising: a piston operatively mounted in a cylinder defined by said cylinder head, said rocker arm having oppositely extending arms and provided with a vertically extending opening between said arms and a concave curved surface extending upward from said opening, said piston having one end extended upwardly through said opening and forming a pivot upon which said rocker arm is pivotably mounted; a source of fluid connected with the pressure lubricating system of said engine; a chamber defined by said engine; means for hydraulically connecting said source of fluid to said chamber; means for hydraulically connecting said chamber to said cylinder; and check valve means comprising a ball positioned in said chamber and coacting with said first named means to prevent said fluid in said cylinder from returning to said source of fluid.

References Cited in the file of this patent UNITED STATES PATENTS 1,786,716 Kauflman et al Dec. 30, 1930 1,937,932 Woolman Dec. 5, 1933 2,075,597 Zahodiakin Mar. 30, 1937 2,669,981 Leach Feb. 23, 1954 FOREIGN PATENTS 436,744 Great Britain Oct. 17, 1935 U. S. DEPARTMENT OF COMMERCE PATENT OFFICE CERTIFICATE OF CORRECTION Patent No 2,824,553 February 25, 1958 Aldo Celli It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction and that the said Let ters Patent should read as corrected below.

Column 2, line 39, for "outer" "read =--'=-'other==; line 43, for "afor= mentioned" read -==aforementioned lines 60 and 61, after "suitable" "insert seal= Signed and sealed this 15th day of April 1958o (SEAL) Atteet:

KARL Ha AXLINE ROBERT C. WATSON Attesting Officer Conmissioner of Patents 

